1. Field of the Invention
This invention relate, generally to lockout valves for implantable penile prostheses, and particularly to a valve assembly which responds to an internal pressure differential within the prosthesis and which may be retrofitted to an existing implanted prosthesis.
2. Content of the Prior Art
Implantable penile prostheses for treating impotence are well know to the art. These prostheses generally include a reservoir of biocompatible liquid such as physiological saline implanted within the patient s abdomen, a pump and valve block located within the patient's scrotum, and a pair of cylinders which are implanted within the corpus cavernosae of the penis. Actuating the pump transfers fluid from the reservoir to the cylinders causing them to inflate, thus producing an erection. When the patient wishes to return to a tumescent or flaccid state, he releases the fluid from the cylinders back into the reservoir, in some cases by manually compressing the cylinders to force fluid back to the reservoir. Some representative examples of these penile prostheses and their components or variations are shown in several United States patents to Buuck '102, Cowen '611, '417, '485, and '914, Fogarty '446, 183, and '826, Bley '020, Uson '711, and Strauch '122, which are incorporated herein by reference.
A wide variety of embodiments of such penile prostheses are known, including the representative examples mentioned above. For example, some prostheses do not utilize a pump, but rather rely on physical compression of the reservoir or a pressurized reservoir to inflate the cylinders. While some prostheses locate the reservoir or pump subcutaneously within the patient's abdomen, others provide a unitary pump and reservoir located within the patient's scrotum. For purposes of this disclosure, many of these prostheses may be considered substantially interchangeable to the extent they include a reservoir, pump, and cylinders (or their structural or functional equivalents).
As noted, one of the components of many prostheses is a valve block, which contains one or more check valves regulating the flow of fluid between the reservoir and cylinders. These check valves prevent the flow of fluid in one direction, and may be spring-biased to remain in a closed position preventing flow in the forward direction until sufficient internal pressure is exerted on the valves to cause them to open. In some embodiments, the check valves are actually palpitatable valves which must be physically manipulated (such as by actuating the pump or squeezing the valve element) in order to open the valve to forward flow.
Another component is a release or relief valve, which serves to permit reverse flow from the cylinders to the reservoir when the release valve is selectively actuated by the patient. The release valve is usually located in the pump or valve block, between the pump and the cylinders, or within or near the cylinders.
While the check valves and release valves are suitable to selectively control the flow of fluid between the reservoir and the cylinders during normal operation, it was soon recognized that pressure exerted on the reservoir during physical activity or movement by the patient could cause the inadvertent and undesired inflation of the cylinders. If sufficient pressure is placed on the reservoir (for example, when a patient who has an abdominal reservoir bends over, or a patient having a scrotal reservoir sits down or crosses his legs), the pressure on the reservoir may overcome the resistance of the spring-biased check valve, causing complete or partial inflation of the cylinders. In prostheses having pressurized reservoirs, the unintended activation of the control valve can produce the same result. In the event of accidental auto-inflation--either partial or total--the patient would be required to manually open the release valve and physically compress the cylinders to deflate them.
In addition, encapsulation or calcification frequently occurs around the reservoir. This can lead to more frequent instances of auto-inflation (since the capsule may transmit or focus more pressure on the reservoir when the patient moves or bends), or result in continuous partial inflation because the capsule exerts pressure on the reservoir that overcomes the check valve or prevents complete deflation of the cylinders.
As may be readily appreciated, instances of accidental auto-inflation can be quite embarrassing and painful for a patient, and may restrict their ability to engage in certain recreational or daily activities. In addition, even for patients whose actual incidents of accidental auto-inflation might be infrequent, the mere risk of such an occurrence may cause them to refrain from activities in which they might otherwise engage.
Lockout valves to prevent auto-inflation of the chambers are therefore well known to the art. As meant herein, the term "lockout valve" means a valve or flow control other than the check or release valves, which serves to prevent accidental auto-inflation and is characterized by requiring selective actuation or activation by the patient in order to permit fluid flow in the positive direction (i.e., from the reservoir to the cylinders), and which will remain closed despite high fluid pressures experienced by or exerted from fluid in the reservoir or connecting tubing.
Conventional lockout valves include those which are normally-closed (returning to a completely closed position when not being manually actuated) versus bi-stable (having distinct open and closed positions in which the valve will remain until manually moved to the contrary position).
Representative examples of various lockout valves are shown in several United States and foreign patents, the disclosures of which are incorporated herein by reference.
The Cozzi '798 patent application discloses a prostheses having an abdominal reservoir with either a palpitatable or bi-stable "spigot" type lockout valve located in the scrotum. The Cozzi '798 patent does not utilize a pump, but instead relies on manual compression of the reservoir. The Trick '110 patent shows a bi-stable lever-type valve mounted on a pressurized reservoir located within the scrotum. The Stucks '416 patent provides bi-stable valves associated with each cylinder which control both inflation and deflation.
The Evans '491 and 968 patents disclose bi-stable crossover valves which are connected in line between the pump and cylinders. The Burton '509 patent discloses an embodiment having a bi-stable valve located in the valve block, and an embodiment in which the valve actuator is located inside the pump bulb.
The Daly '403 and Trick '360 patents disclose palpitatable valves which are formed integrally with the pump and are therefore located within the patient's scrotum. The Lash '693 patent shows a palpitatable valve disposed slightly downstream from the unitary pump and reservoir.
The Fischell '242 and '830 patents disclose subcutaneous lockout valves positioned within the patient's abdomen or pubic area, which are opened by depressing a spring-biased plunger or resilient diaphragm.
Although not exhaustive of the various structures and embodiments of lockout valves developed or utilized with inflatable penile prostheses, these examples are believed to represent the basic concepts or methods previously employed by those skilled in the art of designing penile prostheses to prevent accidental auto-inflation.
However, these designs do present or reflect several significant disadvantages or drawbacks.
Several of the lockout valves require two-handed operation--one to actuate the lockout valve, and the other to operate the pump or compress the reservoir. It may also be difficult to initially locate or manipulate the activation mechanisms in some of the lockout valves.
Subcutaneous abdominal lockout valves may become less responsive when implanted due to calcification and the formation of scar tissue, or due to movement within the patient unless the lockout valve is secured to an available anatomical structure.
Some of the lockout valves can cause additional discomfort due to their size or shape, or may expose the patient to the risk of internal injuries or damage due to interference with vesicles or lumen within the scrotum, or as a result of manipulating the valve's actuation mechanism. The size and shape of some lockout valves may increase the complexity or risks associated with the implant procedure itself, or prohibit some types of less invasive surgical procedures.
Finally, some of the valves are unduly complicated or expensive to manufacture, and may be subject to mechanical wear, failure, or rejection that would necessitate repair or replacement, thereby involving additional surgery for the patient.